Blood spatter, or blood stain analysis, is a technique used to identify events that happened at a crime scene. Knowing how the blood got onto a surface helps determine when and how it happened. The first step for the forensic investigator is to verify that the substance is in fact blood. This can be done by using tests portable to the crime scene, such as spraying a chemical liquid on the blood and turning off the lights, if it was in fact blood, then it will illuminate. Once you determine it is blood, then there are many ways to find out what really happened at the crime scene You can determine how fast the person was moving, what order the blood trail is in, etc.
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